Various types of forming dies have been developed for forming a wide variety of metal part configurations, particularly in the automotive industry. One example of such a forming die utilizes a rotary cam in order to form a negative-angle on piece of sheet metal. A “negative angle” or “back draft” is broadly defined as any angle formed in a metal work piece where at least a portion of the formed section extends more inwardly than a straight downward stroke line (beyond 90°), and is appreciated by those skilled in the art.
It is known in the art to provide a forming die with a lower die half, an upper die half, an upper die pad, a work cam and a rotary cam for forming a piece of sheet metal. The work piece is placed on a post of the lower die half and the rotary cam, then the upper die half is lowered causing the upper die pad to clamp the piece of sheet metal to the lower die post and rotary cam, prior to forming. Next, a work cam (which can be mounted to either the upper or lower die halves) is driven such that the sheet metal work piece is formed to the desired shape. The upper die half continues being lowered until a desired shut height between the upper and lower die halves is achieved. Once the final formed shape is complete the upper die half is raised and the two die halves separate so that the formed sheet metal can be removed.